Wow! This is a really really big discussion and way of life that I continually discover and practice. I do have some simple tips though that can help you wrap your brain around this massive topic.
Also side note.. I am moving along this journey with you on all posts I write about. I am an eternal student on this earth plain in this moment and all moments before and after.
First, lets talk about time and time lines. Ok.. open your mind a bit here.. time is not real, time is an illusion. Yep let that settle in for a bit. There are many different times lines, many different dimensions that our being exists in. There is a version of you in another now moment that is the manifestation of your current thoughts and actions. You now are a manifestation of a previous now moments thoughts and actions.
So what does this mean for manifestation? The best and fastest way to manifest something is to feel the feeling you will feel when you are living in the manifested reality. For example, if you want abundance in the way of health, maybe a number on the scale... feel the feeling of how you will feel when you at that ideal weight. When you feel that feeling of your manifested reality you start to conjure up more thoughts and more positive feelings around your goal. That starts the abundance snow ball effect. One positive thought turns into another and another and then a positive feeling and another... Focus on the feeling rather than what your perceive the outcome to be.
If you can simply realize that manifestation is a by product of your attention to your feelings you will begin to see the magic unfold.